After doing so all players that are based on ffmpeg are able to play audio or video files encoded with one of the supported codecs. This also includes players that come with a standard Ubuntu installation.

if you are willing to try a new media player I recommend vlc (sudo apt-get install vlc from terminal) and is often on the front page of the software centre if you don't like vlc you could use UMplayer,Xine or XBMC (great for home theater) other methods are covered in other answers